Rf circuit module

ABSTRACT

A module for radio frequency signal circuits includes an electrically conductive housing. Coax connectors are secured to the rear face of the housing. A circuit board is contained within the interior spaced between sidewalls of the housing. A ground side of the circuit board includes a layer of electrically conductive material which is electrically connected to the housing. Coax cables extend within the interior of the housing from the coax connectors and between the ground side of the circuit board and an opposing sidewall. An opposite side of the circuit board contains circuit components interconnected with one another through a plurality of circuit paths.

This application is a Continuation of application Ser. No. 08/761,525,filed Dec. 6, 1996, U.S. Pat. No. 6,049,709.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to circuits for broad-band RF systems. Moreparticularly, this invention pertains to modular RF (radio frequency)circuit components.

2. Description of the Prior Art

In the telecommunications industry and more particularly in the videotransmission industry, broad-band radio frequency (RF) signals (i.e., 5MHz to 1 GHz) are carried over coax conductors from a headend toconsumers. At the headend of the system, numerous signals aremanipulated to achieve a wide variety of functions and objectives. Forexample, signals carried on numerous coax cables may be combined onto asingle coax conductor. Similarly, a signal on a main coax conductor maybe divided into a plurality of signals carried on branch coaxconductors. Additionally, signals may be added or removed from a mainconductor through directional couplers or the like.

In addition to combining, splitting, diverting or adding signals, theheadend will also include apparatus for modifying signals. For example,in order to adequately tune the system, it may be desirable to provideattenuators or the like to attenuate a signal to a desired level.Further, as a broadband RF signal is carried over a length of cable, thehigh frequency range of the signal may be attenuated more than a lowfrequency range of the signal. As a result, equalizers are utilized tomodify the signal to have a level intensity throughout its frequencyrange.

Throughout the system, performance characteristics are critical. Forexample, a common performance criteria is to maintain the flatness of asignal. Flatness refers to maintaining a level intensity of a signalthroughout its frequency range. For example, if the signal is attenuatedby 2 dB at 1 Ghz, then it is desirable that the signal be attenuated at2 dB at the 5 Mhz frequency. Further, the system needs to be tuned forimpedance matching.

Prior art headends include a wide variety of devices to accommodate andaccomplish the functions described above. It is desirable to provide anapparatus to accommodate the various functions required at the headendthrough a modular construction to permit ease of maintenance and cablemanagement in a headend. Such a device must accommodate the performancecharacteristics of the headend while permitting the modular constructionto enhance the cable management and organization of a headend.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the present invention, a moduleis provided for containing a circuit for performing discrete functionson a radio frequency signal. The module comprises a housing ofelectrically conductive material. The housing has a front face and anopposite rear face. The front face and rear face are separated byopposite sidewalls and opposite end walls. A plurality of coaxconnectors are secured to the rear face with an outer shield of theconnectors electrically connected to the housing. A circuit board iscontained within the interior. The circuit board is generally parallelto and spaced between the sidewalls. The circuit board has a componentside and a ground side. The ground side includes a layer of electricallyconductive material which is electrically connected to the housing. Aplurality of coax cable connection locations are provided on the groundside of the circuit board. Each of the coax cable connections includes aground connection for connecting ground shields of coax cables to thelayer of electrically conductive material. The component side of thecircuit board includes a plurality of circuit components interconnectedwith one another and with the coax cable connection locations through aplurality of circuit paths. A plurality of coax cables are disposedwithin the interior and connected to individual ones of the coaxconnectors and the coax cable connection locations. Each of the coaxcables has a ground shield connected to the outer shields of theconnectors and to the ground connections of the coax cable connectionlocations. A plurality of cables are routed for the cables to bedisposed between the ground side of the circuit board and the opposingsidewall of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom end, front face and right sidewall perspective viewof one embodiment of a module according to the present invention shownin exploded view (with internal cables omitted);

FIG. 2 is a left side plan view of the module of FIG. 1;

FIG. 3 is a right side plan view of the module of FIG. 1;

FIG. 4 is a front elevation view of the module of FIG. 1;

FIG. 5 is a rear elevation view of the module of FIG. 1;

FIG. 6 is a bottom end view of the module of FIG. 1;

FIG. 7 is a top end view of the module of FIG. 1;

FIG. 8 is a rear, right side and top end exploded view of the module ofFIG. 1 with a cover removed;

FIG. 9 is a perspective view of internal components of the module ofFIG. 1;

FIG. 9A is a top plan view of a printed circuit board and attachedcomponents;

FIG. 10 is an opposite side plan view of the components of FIG. 9;

FIG. 11 is a side cross-sectional view of the module of FIG. 1;

FIG. 12 is a view similar to that of FIG. 1 showing in exploded formatan alternative embodiment of the present invention;

FIG. 13 is a right side plan view of the module of FIG. 12;

FIG. 14 is a left side plan view of the module of FIG. 12;

FIG. 15 is a front elevation view of the module of FIG. 12;

FIG. 16 is a rear elevation view of the module of FIG. 12;

FIG. 17 is a bottom end view of the module of FIG. 12;

FIG. 18 is a top end view of the module of FIG. 12;

FIG. 19 is a bottom end, front face and right sidewall perspective viewof a third embodiment of a module according to the present inventionshown in exploded view (with internal cables omitted);

FIG. 20 is a right side plan view of the module of FIG. 19;

FIG. 21 is a left side plan view of the module of FIG. 19;

FIG. 22 is a front elevation view of the module of FIG. 19;

FIG. 23 is a rear elevation view of the module of FIG. 19;

FIG. 24 is a bottom end view of the module of FIG. 19;

FIG. 25 is a top end view of the module of FIG. 19;

FIG. 26 is a perspective view of a first embodiment of a chassis forholding modules according to the present invention;

FIG. 27 is a perspective view of a second embodiment of a chassis forholding modules of the present invention; and

FIG. 28 is a perspective view of a third embodiment of a chassis forholding modules of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the several drawing figures in which identical elementsare numbered identically throughout, a description of the preferredembodiment of the present invention will now be provided.

With initial reference to FIGS. 1 through 11, a module 10 according tothe present invention will be described for use as a splitter/combinermodule for splitting a main signal into a plurality of branch signalsor, alternatively, combining a plurality of branch signals into a commonmain signal. The module 10 includes a housing having a front face 14, arear face 16. The front face and rear face 14, 16 are separated byopposing sidewalls 18, 20 and opposite end walls 22, 24. The housing 12is formed of electrically conductive material. Preferably, the materialis nickel-plated aluminum.

Sidewall 18 and end walls 22, 24 are integrally formed as a boxconfiguration with walls 22, 24 having inwardly protruding peripheralledge 26. Rear wall 16 is secured to walls 18, 22, 24 by screws 28. Thesidewall 20 is fastened to the ledge 26 by a plurality of screws 28received in aligned bolt holes of sidewall 20 and threaded bolt holes 32on the peripheral ledge.

The sidewall 20 is sized to have a length greater than the longitudinaldimension between walls 22,24 such that ends 20 a, 20 b extend beyondends 22, 24 as flanges for purposes that will be described.

The front cover 14 includes extending edges 14 a, 14 b which extendbeyond ends 22, 24. The front cover further has an internal ledge 34(shown in FIGS. 1, 8 and 11) on an interior surface of the cover 14. Theledge 34 is sized to extend into the interior of the housing when thefront cover 14 is attached to the housing.

The front cover 14 and sidewall 20 are secured to the housing by thescrews 28 received within aligned bolt holes. The screws 28 arepreferably positioned at one-half inch on-center spacings to prevent EMIleakage as is conventional.

The front cover 14 includes a plurality of openings 36 the function ofwhich will be described with the openings 36 arranged linearly along theface 14. Similarly, the front cover 14 includes an opening 38 sized topass a coax connector 41 for purposes that will become apparent.

A plurality of coax connectors 40-0 through 40-8 are secured to the rearface 16. Each of the coax connectors is identical. Such connectors areconventional and include a central conductor surrounded by a groundedshield. The grounded shields of the coax conductors are in directphysical and electrical contact with the electrically conductivematerial of the rear face 16.

Contained within the interior of the housing 12 is a printed circuitboard 44. The printed circuit board 44 is supported on posts 42 byscrews 43. The posts 42 are electrically conductive and connected towall 18. The printed circuit board 44 includes a component side 44 a anda ground side 44 b (see FIG. 9). The ground side 44 b opposes the wall18 and the component side 44 a opposes wall 20. The printed circuitboard 44 is maintained in parallel, spaced relation between the walls18, 20 by supports 42.

A layer 44 c (FIG. 9) of electrically conductive material (such as asheet layer of copper) is provided on the exterior surface of surface 44b.

A plurality of coax cable connection locations 48-0 through 48-8 areprovided on the ground side 44 b of the printed circuit board 44. Eachof the coax cable connection locations 48-0 through 48-8 include aground connection for connecting the ground shields of a coax cable tothe conductive layer 44 c.

A plurality of circuit components are disposed on the component side 44a of the printed circuit board 44. In the embodiment shown, thecomponents include a solid state directional coupler 50 and three solidstate splitter/combiners 52-1, 52-2 and 52-3.

It will be appreciated that a solid state directional coupler 50 is acommercially available item, and an example of such is a 20 dB couplerProduct No. CPL/20BE-08A3 sold by TRAK Microwave, 4726 Eisenhower Blvd.,Tampa, Fla. 33634-6391. Similarly, solid state splitter/combiners 52-2through 52-3 are commercially available one-by-four splitters andexamples of such are Product No. SPL/4BE-53D sold by TRAK Microwave.Splitter/combiner 52-1 is a one-by-two splitter such as Product No.SPL/2BE-53D of TRAK Microwave.

The splitter/combiners each receive a signal and divide an RF signalinto two signals of equal strength. Splitter/combiners 52-2 and 52-1 areelectrically connected in series. Similarly, splitter 52-3 is connectedin series with splitter 52-1 such that splitter 52-3 is connected inparallel to splitter 52-2.

The electrical connection of the components 50 and 52-1 through 52-3 isprovided through a plurality of circuit paths 53 (FIG. 9A) contained onthe surface 44 a where the circuit paths connect the components 50, 52-1and 52-3 with the coax connection locations 48-0 through 48-8. Thecircuit paths connect the components and the connection locations suchthat connector 40-0 is connected to the directional coupler 50 with aportion of the signal diverted from the directional coupler 50 to thecoax monitor connector 41 through cable 41-1. Preferably, coupler 50provides a −20 dB monitor signal.

The main signal from the directional coupler 50 is passed to thesplitter/combiner 52-1 which divides the main signal into two signalswith one passed along the circuit paths to splitter/combiner 52-2 andthe other passed to splitter/combiner 52-3. Each of splitters 52-2 and52-3 split a signal into four signals resulting in a total of eightbranch signals passed to connection locations 48-1 through 48-8.

In the preceding paragraph, a signal is described as coming into thedirectional coupler from connector 40-0 and then eventually split andpassed to connectors 40-1 through 40-8. With the directional coupler 50arranged in the schematic shown of FIG. 3, such a signal flow path wouldresult in losing a monitor function at monitor port 41. With thisschematic shown in FIG. 3, signals passed into connectors 40-1 through40-8 are attenuated and combined to a main signal which is then passedthrough directional coupler 50 to OUT port 40-0. A portion of the mainsignal is then passed from the directional coupler 50 to the monitorport 41 so that the signal may be monitored. If it is desirable to passa signal into connector 40-1 for division into branch signalsdistributed to connectors 40-1 through 40-8, a different directionalcoupler 50 can be provided such that a signal from connector 40-0 can bemonitored at port 41.

Before the branch signals are passed to the connection locations, theyare passed through attenuator components. Each of the attenuatorcomponents is identical and includes a base member 60-1 through 60-8which is secured to the component side 44 a of the printed circuit board44 along a leading edge 44 d of the printed circuit board and with thebase members 60-1 through 60-8 arranged in a linear array.

A plurality of the attenuator plugs 64-1 through 64-8 are provided to bereleasably connected to individual ones of the base member 60-1 through60-8. The attenuator plugs 64-1 through 64-8 provide an attenuation toeach of the branch signals being sent to connectors 40-1 throughconnectors 40-8.

Attenuator plugs and base members are commercially available items suchas those sold as Product No. F-7520-A (for a 20 dB attenuator) throughCommunication Associates 1750T-'Coleman Road, Anniston, Ala. 36207. Theplugs 64-1-64-8 can be individually selected to provide a discreteamount of attenuation to a signal. For example, a “zero” plug can beinserted into a base member to provide 0 dB attenuation. Alternatively,at an option of a technician, the 0 dB plug may be replaced with a 15 dBplug to provide 15 dB attenuation to a signal. As a result, each of thebranch circuits can be individually provided with a unique attenuationselected at an option of a technician. The holes 36 on the front face 14are arranged and sized such that each of the attenuator plugs extendsthrough individual ones of the holes 36 to be grasped by an operator. Asa result, an operator can remove and replace an attenuator plug withoutneeding access to the interior of the housing 12.

To provide EMI leakage protection, the front face 14 is provided with aremovable cover 100 surrounding the array of holes 36. A deformable,conductive seal 102 (silicon gasket impregnated with silver particles)is provided between the cover 100 and face 14. Threaded connections 104on the cover 100 are aligned with threaded holes on the standoff posts106 such that the cover 100 can be secured to the face 14 by turning thethreaded connectors 104 into the standoff posts 106. As the threadedconnection 104 is tightened, the edge of the cover 100 compresses intothe seal 102 to thereby compress the seal 102 against the face 14 toprovide an effective EMI seal.

The device thus described performs splitter/combiner functions withconnector 40-0 being a main connector and with connectors 40-1 through40-8 being branch connectors. In other words, a signal admitted toconnector 40-0 is split into eight equal signals passed to connectors40-1 through 40-8. Further, the main signal may be monitored throughforward connector 41.

As shown in the drawings, all of the connectors 40-0-40-8 are connectedto the connection locations 48-0-48-8 via coaxial cables 70-0 through70-8 such that the ground shield of the coaxial cable is electricallyconnected to the ground shield of the connectors 40-0 through 40-8,respectively, as well as connected to the conductive layer 44 c.

In RF circuits, impedance matching is critical. The parallel relation ofthe electrically conductive layer 44 c to the sidewall 18 of the housing12 presents a small capacitance. Further, the spaced relation of thecircuit paths 53 to the opposite sidewall 20 presents a minutecapacitance. Capacitance between the housing and the circuit componentsare referred to as “parasitic reactance”. Further, there is naturalcapacitance or reactance of components on the circuit board 44. Thepathways 53 are tuned to balance the capacitance. The pathways 53 aretuned by adjusting the size of the circuit pathways 53 such that theypresent an inductance selected to balance the parasitic reactances andthe circuit board reactances. It will be appreciated that sizing circuitpathways to present a desired impedance is well known in the art. Also,the cables 70-0 through 70-8 are routed between the ground surface 44 cof the circuit board 44 and its opposing sidewall 18 of the housing 12.By routing the cables 70-8, 70-8 on this side of the circuit board 44and avoiding placing the cables adjacent any of the circuit componentsor circuit pathways, undesirable reactances are avoided.

With the structure thus described, the desired circuit function isattained in a modular format. Further, in addition to impedance matchingcircuit components, the selection and arrangement of components permitsa high performance module with impedance matching throughout and withdesired flatness of a signal across the broad band frequency range.

As shown in the drawings, the forward ledge 34 includes a plurality ofresilient spring contacts 35 mounted on the ledge 34 and positioned toswipe against the electrically conductive layer 44 c as the cover 14 isplaced on to the housing to insure enhanced electrical contact betweenthe conductive layer 44 c and the cover 14 so that all elements aregrounded when coaxial cables are connected to the rear connectors.

To further protect the signal, the front cover 100 is provided on frontend 14 to cover and enclosed all attenuator plugs 64-1-64-8 extendingthrough holes 36. The cover 100 prevents EMI interference which wouldotherwise occur by uncovered plugs 64 extending through holes 36.

The foregoing discussion with respect to FIGS. 1-11 described anembodiment of the present invention for an RF module having splitterfunctions and monitor functions. FIGS. 12-18 illustrate the invention ina different embodiment for an equalizer circuit. In an equalizercircuit, an equalizer component is used to provide the same degree ofattenuation at the extremes of the RF bandwidth. Elements similarlynumbered with respect to the previously described embodiment arenumbered similar in FIGS. 12-18 with the addition of an apostrophe todistinguish between the embodiments.

In FIG. 12, a module 10′ includes a housing having a base 18′ and endwalls 22′, 24′. The module 10′ further includes a front face 14′ and arear face 16′. A side cover 20′ closes the module 10′.

As in the previously described embodiment, the present inventionincorporates a printed circuit board 44′ containing circuit components.The circuit board 44′ is maintained in parallel spaced relation betweenthe sidewall 20′ and the lower sidewall 18′ by support posts 42′ andassociated screws 43′.

For the equalizer circuit, the circuit components include a directionalcoupler 50′ and an equalizer component 64′ removably secured to a basemember 60′. The equalizer 64′ may be removed or replaced through anopening 36′ in the forward wall 14′.

The rear wall 16′ contains coax connectors 40-0′, 40-1′ and 40-2′.Coaxial cables (not shown) extend from the coax connectors 40-0′ through40-2′ and beneath the printed circuit board 44′ in a manner identicalwith that previously described. Further, as in the previous embodiment,the circuit board 44′ contains an electrically conductive layer opposingand electrically connected to surface 18′. Also, the circuit paths onthe upper surface of the board 44′ are provided to balance impedances aspreviously described.

The coaxial cables will extend between the board 44′ and the surface 18′for reasons previously discussed. The circuit paths on the board 44′ aredisposed such that an incoming signal from 40-0′ is passed to theequalizer and then to the directional coupler 50′. Further, the separateincoming signal can be passed from connector 40-1′ to directionalcoupler 50′ encoupled with the signal from the equalizer 64′ with thecoupled signal passed to the output connector 40-2′. A support 51′ ismounted within the interior of the housing to guide equalizer 64′ towardbase member 60′ in required alignment. As with the previous embodiment,a cover 100′ covers the front face 14′ together with a gasket 102′ toprevent EMI.

All other features of the module 10′ are similar to the module 10including the external dimensions and tabs of the module such that amodule 10′ may be interchangeable in a chassis with a module 10.Further, the module 10′ has the same impedance matching and parasiticreactance compensation previously mentioned with respect to module 10.As a result, the invention of module 10 is incorporated into module 10′with module 10′ showing a specific embodiment of the invention for usewith an equalizer component. It will be appreciated that equalizercomponents 64′ are commercially available items. An example of such isproduct number G75-000 of ADC Broadband Communications Division, 999Research Parkway, Meridan, Conn. 06450.

FIGS. 19-25 illustrate a third embodiment of the present invention foruse in a 6-port directional coupler. The directional couplers are usedto split or add multiple signals. Elements similarly numbered withrespect to the previously described embodiments are numbered similarlyin FIGS. 19-25 with the addition of a double apostrophe to distinguishbetween the embodiments.

In FIGS. 19-25, a module 10″ includes a housing 12″ having a base 18″and end walls 22″, 24″. The module 10″ further includes a front face 14″and a rear face 16″. A side cover 20″ closes the module 10″.

As in the previously described embodiments, the present inventionincorporates a printed circuit board 44″ containing circuit components.The printed circuit board 44″ is maintained in parallel spaced relationbetween the sidewall 20″ and the lower sidewall 18″ by support post 42″and associated screws 43″.

The circuit components include six directional couplers 50-1″ through50-6″, each with individually associated attenuator plugs 64-1″ through64-6″ which are removably secured to individual base members 60-1″through 60-6″. Each of the attenuator plugs 64-1″ through 64-6″ may beremoved or replaced through openings 36″ in the forward wall 14″.

The rear wall 16″ contains coax connectors 40-0″ through 40-6″. Coaxialcables (not shown in FIGS.) extend from each of the coax connectors40-0″ through 40-6″ and beneath the printed circuit board 44″ in amanner identical with that described with reference to the firstpreferred embodiment of FIG. 1. Further, as in the previous embodiment,circuit board 44″ contains an electrically conductive layer opposing andelectrically connected to surface 18″. Also, the circuit paths on theupper surface of the board 44″ are provided to balance impedances aspreviously described.

The coaxial cables will extend between the board 44″ and the surface 18″for reasons previously discussed. The circuit paths on the board 44″ aredisposed such that six incoming signals may be separately connected toeach of connectors 40-1″ through 40-6″ and passed through the individualattenuators 64-1″ through 64-6″ into the directional couplers 50-1″through 50-6″ where the six signals will be joined into a common outputsignal passed to connector 40-0″. As with the previous embodiment, acover 100″ covers the front face 14″ together with a gasket 102″ toprevent EMI.

All of the features of the module 10″ are similar to the modules 10, 10′including the external dimensions and tabs of the modules such that themodules 10″, 10′ and 10 may be interchangeable in a common chassis.Further, the module 10″ has the same impedance matching and parasiticreactance compensation previously mentioned with respect to module 10.As a result, the invention of modules 10 and 10′ is incorporated intomodule 10″ with module 10″ showing a specific embodiment of theinvention for use with a 6-port directional coupler circuit.

FIG. 26 shows a first chassis 200 for housing a plurality of modules 10.The chassis 200 includes horizontally spaced apart sidewalls 202,204 andvertically spaced apart top and bottom walls 206,208. The top and bottomwalls 206,208 are spaced apart by a distance substantially equal to adistance between the end walls 22,24 of the module 10.

Each of the top and bottom walls 206,208 includes a plurality ofvertically aligned grooves 210. The grooves 210 are sized to slidablyreceive the projecting flanges 20 a, 20 b of the module 10 such that amodule may be slidably inserted into the frame 200 with the modules 10vertically positioned. In the embodiment shown, there are 12 pairs ofvertically aligned grooves 210 such that 12 modules may be inserted intothe frame 200. Since the flanges 20 a, 20 b of the modules 10 are offsetfrom a longitudinal plane of the module 10, the grooves 210 are offsetfrom module receiving spaces so that the entire open space between thesidewalls of the frame may be filled with modules. Also, the grooves 210are spaced apart a distance selected such that as modules are slidablyinserted into the frame, adjacent modules are positioned with a smallspacing between opposing sidewalls of adjacent modules 10.

Locking screws 214 are provided on the projecting tabs 14 a, 14 b of thefront walls 14 of the modules 10. Corresponding threaded locking holes216 are provided on both the top and bottom walls 206,208 of the frame200. The screws 214 are not centrally positioned on the tabs 14 a, 14 b.Instead, they are laterally offset from a central longitudinal axis ofthe front wall 14. The holes 216 are similarly offset to require that amodule 10 be placed in the frame 200 in a desired orientation and cannotbe flipped 180° to be inserted in an undesired orientation. The frame200 also includes a hinged cover 218 which preferably is transparent topermit an operator to inspect the interior. Cable management brackets220 are provided on the rear of the chassis 200.

From time to time, a customer or purchaser of the modules 10 may desireto hold the modules 10 in a horizontal alignment rather than thevertical alignment of FIG. 26. An alternative chassis 200′ is shown inFIG. 27 for holding the modules 10 in a horizontal alignment. In FIG.27, the chassis 200′ includes horizontally spaced apart sidewalls202′,204′ and vertically spaced apart top and bottom walls 206′,208′. Anintermediate wall 209′ is provided midway and parallel to side walls202′,204′. The distance between either of side walls 202′,204′ andmidwall 209′ is equal to a distance between the end walls 22,24 of themodule 10.

Each of the sidewalls 202′,204′ and the midwall 209′ include a pluralityof horizontally aligned grooves 210′. The grooves 210′ are sized toslidably receive the projecting flanges 20 a, 20 b of the module 10 suchthat a module may be slidably inserted into the frame 200′ with themodule 10 horizontally positioned.

In the embodiment shown in FIG. 27, there are six pairs of horizontallyaligned grooves 210′ on both sides of the center wall 209′ such that theframe 200′ can contain a total of 12 modules. As a result, chassis 200and 200′ give an operator the opportunity to contain the exact samenumber of modules 10 in either a horizontal or a vertical alignment asthe operator may select.

Also, the locking screws 214 of the modules are aligned with lockingholes 216′ on the side walls 202′,204′ and mid wall 209′. Since thescrews 214 are not centrally positioned on tabs 14 a, 14 b, and theholes 216′ are not centrally positioned in modules receiving spaces, amodule 10 must be placed in the frame 200 in a desired orientation andcannot be flipped 180° to an undesired orientation. As in the embodimentof FIG. 26, the frame 200′ of FIG. 27 includes a hinged cover 218′ andcable management brackets 220′.

Finally, FIG. 28 shows a chassis 200″ which may be used in the eventthat an operator does not wish to have a combined total of 12 modulesbut instead only wishes to have a fewer number of modules. Chassis 200′retains two modules 10 in side-by-side horizontal alignment and includesmounting brackets 201 for mounting to a frame structure so that anoperator can elect to mount pairs of modules at a time rather thantwelve modules 10. Frame 200″ is similar to frame 200′ in that it has anintermediate wall 209″ between side walls 202″ and 204″ with the lockingscrews 214 received within holes (not shown) of walls 202″,204″ and209″.

What is claimed is:
 1. A module for containing a circuit for performingdiscrete circuit functions on a radio frequency signal, said modulecomprising: a housing of electrically conductive material defining anenclosed interior; said housing having a front face and an opposite rearface separated by opposite sidewalls and opposite end walls; a pluralityof coax connectors secured to said housing with an outer shield of saidconnectors electrically coupled to said housing; a circuit boardcontained within said interior and positioned generally parallel to andspaced between said sidewalls; said circuit board having a ground layerof electrically conductive material electrically connected to saidhousing; a plurality of connection locations on said circuit board, eachof said connection locations including a ground connection forconnecting to said layer of electrically conductive material; saidcircuit board including a plurality of circuit components interconnectedwith one another and with said connection locations through a pluralityof circuit paths; said coax connectors connected to said connectionlocations, each of said outer shields of said coax connectors connectedto said ground connections of said connection locations, wherein saidcircuit components include at least one removable plug, and a basemember mounted on said circuit board for receiving said plug; saidhousing having a first portion limiting access to said circuit board,said first portion including an opening sized to pass said removableplug so as to access said base member; said housing further including acover portion releasably secured to said first portion and sized tocover said opening.
 2. A module according to claim 1, wherein saidcircuit board includes a component side opposing a first of saidsidewalls and a ground side defining said ground layer opposing a secondof said sidewalls, and further including a plurality of coax cablesdisposed within said interior and connecting said coax connectors tosaid connection locations, each of said coax cables having groundshields connected to said outer shields of said coax connectors and tosaid ground connections of said connection locations, said plurality ofcables routed for said cables to be disposed between said ground side ofsaid circuit board and said second of said sidewalls.
 3. A moduleaccording to claim 1 wherein said circuit paths are sized to have animpedance selected to balance a parasitic reactance between said circuitboard and said housing.
 4. A module according to claim 1 wherein saidplurality of components includes splitter components for receiving amain signal from one of said connection locations and dividing said mainsignal into a plurality of branch signals delivered along said circuitpaths to individual remaining ones of said connection locations.
 5. Amodule according to claim 4 wherein said splitter components are adaptedto act as combiner components for receiving said plurality of branchsignals from said individual ones of said connection locations andcombining said branch signals into said main signal delivered along oneof said circuit paths to said one of said connection locations.
 6. Amodule according to claim 4 wherein said splitter components includes atleast a first splitter and a second splitter connected in series.
 7. Amodule according to claim 6 wherein said splitter components includes athird splitter connected in series with said first splitter and inparallel with said second splitter.
 8. A module according to claim 4wherein said first portion of said housing defines a plurality of saidopenings, wherein said circuit components include a plurality ofattenuators associated with individual ones of said branch signals, saidattenuators defining a plurality of said plugs and said base members,said plugs selected for a desired amount of attenuation for each of saidattenuators, each of said openings sized to pass said plugs.
 9. A moduleaccording to claim 4 wherein said circuit components include a couplerfor diverting a portion of said main signal to a connector locationconnected to a monitor coax connector.
 10. A module according to claim 9wherein said monitor coax connector is exposed on said front face.
 11. Amodule according to claim 1 wherein said circuit components include acoupler.
 12. A module according to claim 11 wherein said circuitcomponents include an equalizer for equalizing a radio frequency signalalong a frequency range, said equalizer defining said plug and said basemember with said plug selected for a desired radio frequencyequalization.
 13. A module according to claim 1 wherein said circuitcomponents include a plurality of directional couplers for receiving aplurality of branch signals delivered along said circuit paths andcombining said branch signals into a main signal at one of saidconnection locations; wherein said first portion of said housing definesa plurality of said openings wherein said circuit components include aplurality of attenuators associated with individual ones of said branchsignals, said attenuators defining a plurality of said plugs and saidbase members, said plugs selected for a desired amount of attenuationfor each of said attenuators, each of said openings sized to pass saidplugs.
 14. A module according to claim 1 wherein said plurality of coaxconnectors are secured to said rear face of said housing.
 15. A moduleaccording to claim 1 wherein said housing includes an end portionextending beyond each of said end walls, and a lock fastener formounting each of said end portions to a frame.
 16. A chassis and modulecombination for permitting selective housing of a plurality of modulescontaining radio frequency circuits, said combination comprising: aplurality of modules, each module having: a housing of electricallyconductive material defining an enclosed interior; said housing having afront face and an opposite rear face separated by opposite sidewalls andopposite end walls; each housing of said plurality of modules includingflanges extending from each of said end walls in a common planegenerally parallel to said sidewalls and with said common plane offsetfrom a central longitudinal axis of each housing; said housing includingan end portion extending beyond one of said end walls; a plurality ofcoax connectors secured to said housing with an outer shield of saidconnectors electrically coupled to said housing; a circuit boardcontained within said interior and positioned generally parallel to andspaced between said sidewalls; said circuit board having a ground layerof electrically conductive material electrically connected to saidhousing; a plurality of connection locations on said circuit board, eachof said connection locations including a ground connection forconnecting to said layer of electrically conductive material; saidcircuit board including a plurality of circuit components interconnectedwith one another and with said connection locations through a pluralityof circuit paths; said coax connectors connected to said connectionlocations, each of said outer shields of said coax connectors connectedto said ground connections of said connection locations; each moduleselected to have a desired function, wherein said circuit components areselected to perform a circuit function on a radio frequency signalsupplied to one of said connectors and to provide an output radiofrequency signal to a remainder of said connectors on each of saidmodules; at least one of said modules including said circuit componentsselected to include at least one removable plug, and a base membermounted on said circuit board for receiving said plug; said housing ofsaid at least one module having a first portion limiting access to saidcircuit board, said first portion including an opening sized to passsaid removable plug so as to access said base member; said housing ofsaid at least one module further including a cover portion releasablysecured to said first portion and sized to cover said opening; a chassisfor receiving the plurality of modules, the chassis including a framewith opposed walls, each wall having a plurality of grooves, each flangeof each module received in a groove, the frame further including a wallportion positioned to engage the end portion of each module, each of thefront faces facing in the same direction; a lock fastener for mountingthe end portion of each module to the wall portion of the frame.
 17. Achassis and module combination according to claim 17 wherein saidplurality of components includes splitter components for receiving amain signalfrom one of said connection locations and dividing said mainsignal into a plurality of branch signals delivered along said circuitpaths to individual remaining ones of said connection locations.
 18. Achassis and module combination according to claim 17 wherein said firstportion of said housing defines a plurality of said openings, whereinsaid circuit components include a plurality of attenuators associatedwith individual ones of said branch signals, said attenuators defining aplurality of said plugs and said base members, said plugs selected for adesired amount of attenuation for each of said attenuators, each of saidopenings sized to pass said plugs.
 19. A chassis and module combinationaccording to claim 17 wherein said circuit components include a couplerfor diverting a portion of said main signal to a connector locationconnected to a monitor coax connector.
 20. A chassis and modulecombination according to claim 19 wherein said monitor coax connector isexposed on said front face.
 21. A chassis and module combinationaccording to claim 16 wherein said circuit components include a coupler.22. A chassis and module combination according to claim 21 wherein saidcircuit components include an equalizer for equalizing a radio frequencysignal along a frequency range, said equalizer defining said plug andsaid base member with said plug selected for a desired radio frequencyequalization.
 23. A chassis and module combination according to claim 16wherein said circuit components include a plurality of directionalcouplers for receiving a plurality of branch signals delivered alongsaid circuit paths and combining said branch signals into a main signalat one of said connection locations; wherein said first portion definesa plurality of said openings wherein said circuit components include aplurality of attenuators associated with individual ones of said branchsignals, said attenuators defining a plurality of said plugs and saidbase members, said plugs selected for a desired amount of attenuationfor each of said attenuators, each of said openings sized to pass saidplugs.
 24. A module for containing a circuit for performing discretecircuit functions on a radio frequency signal, said module comprising: ahousing of electrically conductive material defining an enclosedinterior; said housing having a front face and an opposite rear faceseparated by opposite sidewalls and opposite end walls; a plurality ofcoax connectors secured to said rear face with an outer shield of saidconnectors electrically coupled to said housing; said front face of saidhousing defining an opening; radio frequency circuitry within theenclosed interior of said housing, said radio frequency circuitryelectrically interconnected with said coax connectors of said rear face;said radio frequency circuitry including at least one removable plugsized to pass through said opening in said front face.
 25. A moduleaccording to claim 24, further including a circuit board, and whereinsaid radio frequency circuitry includes a plurality of radio frequencycircuit components mounted to the circuit board, said radio frequencycircuit components interconnected with one another through a pluralityof circuit paths.
 26. A module according to claim 25, wherein saidcircuit board includes a component side opposing a first of saidsidewalls and a ground side defining said ground layer opposing a secondof said sidewalls, and further including a plurality of coax cablesdisposed within said interior and connecting said coax connectors tosaid connection locations, each of said coax cables having groundshields connected to said outer shields of said coax connectors and tosaid ground connections of said connection locations, said plurality ofcables routed for said cables to be disposed between said ground side ofsaid circuit board and said second of said sidewalls.
 27. A moduleaccording to claim 25 wherein said circuit paths are sized to have animpedance selected to balance a parasitic reactance between said circuitboard and said housing.
 28. A module according to claim 25 wherein saidplurality of components includes splitter components for receiving amain signal from one of said coax connectors and dividing said mainsignal into a plurality of branch signals delivered along said circuitpaths to individual remaining ones of said coax connectors.
 29. A moduleaccording to claim 28 wherein said splitter components are adapted toact as combiner components for receiving said plurality of branchsignals from said individual ones of said coax connectors and combiningsaid branch signals into said main signal delivered along one of saidcircuit paths to said one of said coax connectors.
 30. A moduleaccording to claim 28 wherein said splitter components includes at leasta first splitter and a second splitter connected in series.
 31. A moduleaccording to claim 30 wherein said splitter components includes a thirdsplitter connected in series with said first splitter and in parallelwith said second splitter.
 32. A module according to claim 28 whereinsaid front face of said housing defines a plurality of said openings,wherein said circuit components include a plurality of attenuatorsassociated with individual ones of said branch signals, said attenuatorsdefining a plurality of said plugs, said plugs selected for a desiredamount of attenuation for each of said attenuators, each of saidopenings sized to pass said plugs.
 33. A module according to claim 28wherein said circuit components include a coupler for diverting aportion of said main signal to a monitor coax connector.
 34. A moduleaccording to claim 33 wherein said monitor coax connector is exposed onsaid front face.
 35. A module according to claim 25 wherein said circuitcomponents include a coupler.
 36. A module according to claim 35 whereinsaid circuit components include an equalizer for equalizing a radiofrequency signal along a frequency range, said equalizer defining saidplug with said plug selected for a desired radio frequency equalization.37. A module according to claim 25 wherein said circuit componentsinclude a plurality of directional couplers for receiving a plurality ofbranch signals delivered along said circuit paths and combining saidbranch signals into a main signal at one of said coax connectors;wherein said front face of said housing defines a plurality of saidopenings wherein said circuit components include a plurality ofattenuators associated with individual ones of said branch signals, saidattenuators defining a plurality of said plugs, said plugs selected fora desired amount of attenuation for each of said attenuators, each ofsaid openings sized to pass said plugs.
 38. A module according to claim25 wherein said housing includes an end portion extending beyond each ofsaid end walls, and a lock fastener for mounting each of said endportions to a frame.
 39. A module according to claim 38, furthercomprising a removable cover mounted to said front face for coveringsaid removable plug.
 40. A module according to claim 25, furthercomprising a removable cover mounted to said front face for coveringsaid removable plug.
 41. A module according to claim 32, furthercomprising a removable cover mounted to said front face for coveringsaid removable plugs.
 42. A module according to claim 36, furthercomprising a removable cover mounted to said front face for coveringsaid removable plug.
 43. A module according to claim 37, furthercomprising a removable cover mounted to said front face for coveringsaid removable plugs.
 44. A chassis and module combination forpermitting selective housing of a plurality of modules containing radiofrequency circuits, said combination comprising: a plurality of modules,each module having: a housing of electrically conductive materialdefining an enclosed interior; said housing having a front face and anopposite rear face separated by opposite sidewalls and opposite endwalls; each housing of said plurality of modules including flangesextending from each of said end walls in a common plane generallyparallel to said sidewalls and with said common plane offset from acentral longitudinal axis of each housing; said housing including an endportion extending beyond one of said end walls; a plurality of coaxconnectors secured to said rear face with an outer shield of saidconnectors electrically coupled to said housing; said front face of saidhousing defining an opening; radio frequency circuitry within theenclosed interior of said housing, said radio frequency circuitryelectrically interconnected with said coax connectors of said rear face;each module selected to have a desired function, wherein said radiofrequency circuitry is selected to perform a circuit function on a radiofrequency signal supplied to one of said connectors and to provide anoutput radio frequency signal to a remainder of said connectors on eachof said modules; at least one of said modules including said radiofrequency circuitry selected to include at least one removable plugsized to pass through said opening in said front face; a chassis forreceiving the plurality of modules, the chassis including a frame withopposed walls, each wall having a plurality of grooves, each flange ofeach module received in a groove, the frame further including a wallportion positioned to engage the end portion of each module, each of thefront faces facing in the same direction; a lock fastener for mountingthe end portion of each module to the wall portion of the frame.
 45. Achassis and module combination according to claim 44, further includinga circuit board, and wherein said frequency circuitry includes aplurality of radio frequency circuit components mounted to the circuitboard, said radio frequency circuit components interconnected with oneanother through a plurality of circuit paths.
 46. A chassis and modulecombination according to claim 45 wherein said plurality of componentsincludes splitter components for receiving a main signal from one ofsaid coax connectors and dividing said main signal into a plurality ofbranch signals delivered along said circuit paths to individualremaining ones of said coax connectors.
 47. A chassis and modulecombination according to claim 46 wherein said housing defines aplurality of said openings, wherein said circuit components include aplurality of attenuators associated with individual ones of said branchsignals, said attenuators defining a plurality of said plugs, said plugsselected for a desired amount of attenuation for each of saidattenuators, each of said openings sized to pass said plugs.
 48. Achassis and module combination according to claim 46 wherein saidcircuit components include a coupler for diverting a portion of saidmain signal to a monitor coax connector.
 49. A chassis and modulecombination according to claim 48 wherein said monitor coax connector isexposed on said front face.
 50. A chassis and module combinationaccording to claim 45 wherein said circuit components include a coupler.51. A chassis and module combination according to claim 50 wherein saidcircuit components include an equalizer for equalizing a radio frequencysignal along a frequency range, said equalizer defining said plug withsaid plug selected for a desired radio frequency equalization.
 52. Achassis and module combination according to claim 45 wherein saidcircuit components include a plurality of directional couplers forreceiving a plurality of branch signals delivered along said circuitpaths and combining said branch signals into a main signal at one ofsaid coax connectors; wherein said front face defines a plurality ofsaid openings wherein said circuit components include a plurality ofattenuators associated with individual ones of said branch signals, saidattenuators defining a plurality of said plugs, said plugs selected fora desired amount of attenuation for each of said attenuators, each ofsaid openings sized to pass said plugs.
 53. A chassis and modulecombination according to clam 47, further comprising a removable covermounted to said front face of said housing for covering said removableplugs.
 54. A chassis and module combination according to clam 51,further comprising a removable cover mounted to said front face of saidhousing for covering said removable plug.
 55. A chassis and modulecombination according to clam 52, further comprising a removable covermounted to said front face of said housing for covering said removableplugs.
 56. A chassis and module combination according to clam 45,further comprising a removable cover mounted to said front face of saidhousing for covering said removable plug.
 57. A chassis and modulecombination according to clam 44, further comprising a removable covermounted to said front face of said housing for covering said removableplug.
 58. A module for containing a circuit for performing discretecircuit functions on a radio frequency signal, said module comprising: ahousing of electrically conductive material defining an enclosedinterior; said housing having a front face and an opposite rear faceseparated by opposite sidewalls and opposite end walls; a plurality ofcoax connectors secured to said rear face with an outer shield of saidconnectors electrically coupled to said housing; said housing definingan opening; radio frequency circuitry within the enclosed interior ofsaid housing, said radio frequency circuitry electrically interconnectedwith said coax connectors of said rear face; said radio frequencycircuitry including at least one removable plug sized to pass throughsaid opening; wherein said housing includes a removable cover mounted toa remainder of said housing for covering said removable plug.
 59. Amodule according to claim 58 further including a circuit board, andwherein said radio frequency circuitry includes a plurality of radiofrequency circuit components mounted to the circuit board, said radiofrequency circuit components interconnected with one another through aplurality of circuit paths.
 60. A module according to claim 59 whereinsaid circuit board includes a component side opposing a first of saidsidewalls and a ground side defining said ground layer opposing a secondof said sidewalls, and further including a plurality of coax cablesdisposed within said interior and connecting said coax connectors tosaid connection locations, each of said coax cables having groundshields connected to said outer shields of said coax connectors and tosaid ground connections of said connection locations, said plurality ofcables routed for said cables to be disposed between said ground side ofsaid circuit board and said second of said sidewalls.
 61. A moduleaccording to claim 59 wherein said circuit paths are sized to have animpedance selected to balance a parasitic reactance between said circuitboard and said housing.
 62. A module according to claim 59 wherein saidplurality of components includes splitter components for receiving amain signal from one of said coax connectors and dividing said mainsignal into a plurality of branch signals delivered along said circuitpaths to individual remaining ones of said coax connectors.
 63. A moduleaccording to claim 62 wherein said splitter components are adapted toact as combiner components for receiving said plurality of branchsignals from said individual ones of said coax connectors and combiningsaid branch signals into said main signal delivered along one of saidcircuit paths to said one of said coax connectors.
 64. A moduleaccording to claim 62 wherein said splitter components includes at leasta first splitter and a second splitter connected in series.
 65. A moduleaccording to claim 64 wherein said splitter components includes a thirdsplitter connected in series with said first splitter and in parallelwith said second splitter.
 66. A module according to claim 62 whereinsaid housing defines a plurality of said openings, wherein said circuitcomponents include a plurality of attenuators associated with individualones of said branch signals, said attenuators defining a plurality ofsaid plugs, said plugs selected for a desired amount of attenuation foreach of said attenuators, each of said openings sized to pass saidplugs.
 67. A module according to claim 62 wherein said circuitcomponents include a coupler for diverting a portion of said main signalto a monitor coax connector.
 68. A module according to claim 67 whereinsaid monitor coax connector is exposed on said front face.
 69. A moduleaccording to claim 59 wherein said circuit components include a coupler.70. A module according to claim 69 wherein said circuit componentsinclude an equalizer for equalizing a radio frequency signal along afrequency range, said equalizer defining said plug with said plugselected for a desired radio frequency equalization.
 71. A moduleaccording to claim 59 wherein said circuit components include aplurality of directional couplers for receiving a plurality of branchsignals delivered along said circuit paths and combining said branchsignals into a main signal at one of said coax connectors; wherein saidhousing defines a plurality of said openings wherein said circuitcomponents include a plurality of attenuators associated with individualones of said branch signals, said attenuators defining a plurality ofsaid plugs, said plugs selected for a desired amount of attenuation foreach of said attenuators, each of said openings sized to pass saidplugs.
 72. A module according to claim 59 wherein said housing includesan end portion extending beyond each of said end walls, and a lockfastener for mounting each of said end portions to a frame.
 73. A moduleaccording to claim 66 wherein said removable cover covers all of saidremovable plugs.
 74. A module according to claim 71 wherein saidremovable cover covers all of said removable plugs.
 75. A chassis andmodule combination for permitting selective housing of a plurality ofmodules containing radio frequency circuits, said combinationcomprising: a plurality of modules, each module having: a housing ofelectrically conductive material defining an enclosed interior; saidhousing having a front face and an opposite rear face separated byopposite sidewalls and opposite end walls; each housing of saidplurality of modules including flanges extending from each of said endwalls in a common plane generally parallel to said sidewalls and withsaid common plane offset from a central longitudinal axis of eachhousing; said housing including an end portion extending beyond one ofsaid end walls; a plurality of coax connectors secured to said rear facewith an outer shield of said connectors electrically coupled to saidhousing; said housing defining an opening; radio frequency circuitrywithin the enclosed interior of said housing, said radio frequencycircuitry electrically interconnected with said coax connectors of saidrear face; each module selected to have a desired function, wherein saidradio frequency circuitry is selected to perform a circuit function on aradio frequency signal supplied to one of said connectors and to providean output radio frequency signal to a remainder of said connectors oneach of said modules; at least one of said modules including said radiofrequency circuitry selected to include at least one removable plugsized to pass through said opening, wherein said housing includes aremovable cover mounted to a remainder of said housing for covering saidremovable plug; a chassis for receiving the plurality of modules, thechassis including a frame with opposed walls, each wall having aplurality of grooves, each flange of each module received in a groove,the frame further including a wall portion positioned to engage the endportion of each module, each of the front faces facing in the samedirection; a lock fastener for mounting the end portion of each moduleto the wall portion of the frame.
 76. A chassis and module combinationaccording to claim 75 further including a circuit board, and whereinsaid frequency circuitry includes a plurality of radio frequency circuitcomponents mounted to the circuit board, said radio frequency circuitcomponents interconnected with one another through a plurality ofcircuit paths.
 77. A chassis and module combination according to claim76 wherein said plurality of components includes splitter components forreceiving a main signal from one of said coax connectors and dividingsaid main signal into a plurality of branch signals delivered along saidcircuit paths to individual remaining ones of said coax connectors. 78.A chassis and module combination according to claim 77 wherein saidhousing defines a plurality of said openings, wherein said circuitcomponents include a plurality of attenuators associated with individualones of said branch signals, said attenuators defining a plurality ofsaid plugs, said plugs selected for a desired amount of attenuation foreach of said attenuators, each of said openings sized to pass saidplugs.
 79. A chassis and module combination according to claim 77wherein said circuit components include a coupler for diverting aportion of said main signal to a monitor coax connector.
 80. A chassisand module combination according to claim 79 wherein said monitor coaxconnector is exposed on said front face.
 81. A chassis and modulecombination according to claim 76 wherein said circuit componentsinclude a coupler.
 82. A chassis and module combination according toclaim 81 wherein said circuit components include an equalizer forequalizing a radio frequency signal along a frequency range, saidequalizer defining said plug with said plug selected for a desired radiofrequency equalization.
 83. A chassis and module combination accordingto claim 76 wherein said circuit components include a plurality ofdirectional couplers for receiving a plurality of branch signalsdelivered along said circuit paths and combining said branch signalsinto a main signal at one of said coax connectors; wherein said housingdefines a plurality of said openings, wherein said circuit componentsinclude a plurality of attenuators associated with individual ones ofsaid branch signals, said attenuators defining a plurality of saidplugs, said plugs selected for a desired amount of attenuation for eachof said attenuators, each of said openings sized to pass said plugs. 84.A chassis and module combination according to claim 78 wherein saidremovable cover covers all of said removable plugs.
 85. A chassis andmodule combination according to clam 83 wherein said removable covercovers all of said removable plugs.
 86. A module for containing acircuit for performing discrete circuit functions on a radio frequencysignal, the module comprising: a housing including circuit housingstructure defining an interior, said circuit housing structure includingelectrically conductive material; said circuit housing structure havinga front and a back, said circuit housing structure also includingopposite side walls that extend between said front and back, saidcircuit housing structure further including opposite end walls thatextend between said side walls and also extend between said front andback of said circuit housing structure; a plurality of coax connectorsmounted at said back of said circuit housing structure with outershields of said connectors electrically coupled to said circuit housingstructure; radio frequency circuitry at least partially within saidinterior of said circuit housing structure, said radio frequencycircuitry being electrically interconnected with said coax connectors;said radio frequency circuitry including at least one removable plugthat is accessible from said front of said circuit housing structure.87. The module according to claim 86 wherein said housing includes acover structure, said cover structure covering at least said plug, andsaid cover structure being removable from said circuit housing structureto allow said plug to be accessed.
 88. The module according to claim 86wherein said circuit housing structure includes front face structure;said front face structure defining an opening; said plug sized to passthrough said opening.
 89. A module for containing a circuit forperforming discrete circuit functions on a radio frequency signal, saidmodule comprising: a housing including a first structure defining aninterior, said first structure including electrically conductivematerial; said first structure having a front and a back, said firststructure also including opposite side walls that extend between saidfront and back, said first structure further including opposite endwalls that extend between said side walls and also extend between saidfront and back of said first structure; a plurality of coax connectorsmounted at said back of said first structure with outer shields of saidconnectors electrically coupled to said first structure; radio frequencycircuitry at least partially within said interior of said firststructure, said radio frequency circuitry being electricallyinterconnected with said coax connectors; said radio frequency circuitryincluding at least one removable plug that is accessible from said frontof said first structure; and said housing including a second structurein said form of a removable cover mounted at said front of said firststructure for covering at least said plug, said cover being removablefrom said first structure to allow said plug to be accessed.
 90. Themodule according to claim 89 wherein said first structure includes frontface structure; said front face structure defining an opening; said plugsized to pass through said opening.
 91. A module for containing acircuit for performing discrete circuit functions on a radio frequencysignal, said module comprising: a housing including a first structurecomprising electrically conductive material defining an interior; saidfirst structure having a front and a back; a plurality of coaxconnectors secured to said back with an outer shield of said connectorselectrically coupled to said first structure; radio frequency circuitrypositioned at least partially within said first structure, said radiofrequency circuitry electrically interconnected with said coaxconnectors; said radio frequency circuitry including at least oneremovable plug that is accessible from said front of said firststructure; said first structure including front face structure, saidfront face structure defining an opening, and said plug sized to passthrough said opening; said housing including a second structure thatcovers at least said plug, said second structure being removable fromsaid first structure so that said plug can be accessed.